Pfizer Inc., the world’s biggest drugmaker, filed a patent-infringement lawsuit against four companies including Apotex Inc. and Mylan Inc. to block sales of generic versions of the erectile-dysfunction drug Viagra.

Apotex, Mylan, Amneal Pharmaceuticals LLC and Actavis Inc. applied to the Food and Drug Administration to sell copies of sildenafil citrate, the active ingredient in Viagra, according to the lawsuit Friday in the U.S. District Court for the Southern District of New York.

The nation's largest grocery chain is trying to leap into the driverless delivery market, announcing Tuesday that it is now ready to bring milk, eggs and apples to some customers' homes in a vehicle with nobody at the wheel.

Uncertainty may be flooding the health care market after a Texas judge’s ruling on the Affordable Care Act, but in Colorado there is some good news: there's another sign pointing to the individual market stabilizing.